1. Field of the Invention
The present invention relates to a method for the growth promotion of animals, and to a powder composition containing killed microbial cells of bacteria belonging to genus Clostridium.
2. Related Art Statement
Antibacterial substances such as antibiotics are widely used as additives for feeds, for the purpose of growth promotion of domestic animals, fowls and cultured aquatic animals.
However, it has been often pointed out by consumers, informants of mass media, etc., that there is a serious problem regarding antibacterial substances found in the flesh of domestic animals, fowls and cultured aquatic animals Therefore, intensive research is being made about the use of antibacterial substances, from a standpoint of the supply of foods safe for human consumption, i.e. highly safe foods.
On the other hand, since old time, use has been made of microbial compositions containing probiotics for the purpose of keeping mammalian animals, including human beings and domestic animals, healthy. It is generally considered that such compositions will have an antagonistic activity against pathogenic bacteria, and that the presence of useful viable bacteria is believed to be indispensable for said compositions accordingly.
In the case of microbial compositions containing probiotics, it is not preferable to heat them in view of protein denaturation, and therefore such compositions cannot be formulated into crumbles and pellets having high strength. In cases where amylase secreting probiotics (such as bacteria belonging to genus Clostridium) are added to the pasty feeds containing .alpha.-starch as binders (such as feeds for cultured eels), such feeds may be deteriorated by the action of such amylase. Furthermore, in cases where the probiotics are spore-forming bacteria, it is necessary to subject them to a spore-forming treatment in order to sufficiently avoid the death of bacteria, and therefore such microbial compositions will be produced with a low yield.
It is therefore an object of the invention to provide growth promotion substances, which can be safely used instead of known antibacterial substances and microbial compositions containing probiotics.